We propose to continue to apply aa in vitro model system; viz., organotypic cultures of mammalian nerve tissues, to problems of neurobiological and neuropathological interest. Principal among these are investigations related to the demyelinative diseases in which aseries of experiments are in progress. These studies are directed toward the examination of the immunological and virological hypotheses of the etiology and pathogenesis of multiple sclerosis. In addition, we are continuing our investigations of toxic, metabolic and genetic factors as they may affect the development, maintenance and functions of the nervous system.